The Messenger of Allah ﷺ loved for the Muhajirun and the Ansar to stand directly behind him in prayer.
حدثنا معتمر عن حميد
كان رسول الله ﷺ يحب أن يليه المهاجرون والأنصار في الصلاة
Its isnad is sahih, and Mutamir traces it up to Humayd. Abu Dawud narrated the hadith in 1/180, no. 674, in the Book of Prayer, chapter on who is preferred to stand next to the imam, Tirmidhi in 1/442, no. 228, in the Book of Prayer Times, chapter on what has been reported regarding "let those closest to me in you stand next to me," and Ibn Majah in 1/313, no. 977.